Hair consists of many long, parallel chains of amino acids. These chains, or polymers, of amino acids are bound to each other via 1) hydrogen bonding, 2) salt bridges between acid and base groups, and 3) disulfide bonds.
At alkaline pH, the disulfide bonds in hair can be broken (Dombrink et al., Chem Matters, 1983, page 8). For example, lye-based relaxers contain hydroxide ions which attack the disulfide linkages. The cleavage of disulfide bonds by the lye-based relaxer is used to achieve straightening of the hair through changing of the relative positions of polypeptide chains. The straightening process is completed by rinsing the hair and/or application of a neutralizing formulation.
While lye and other alkali-based relaxers are highly effective at relaxing and straightening hair, they can result in reduction of hair strength and potential loss of hair through breakage.
Additionally, it is well known that lye and alkali-based relaxers cannot be used to perm hair.
Traditional perms are performed using thiol based reducing agents followed by a second oxidizing step, typically using hydrogen peroxide, to set the hair. These thiol based reducing agents are foul smelling and if not properly rinsed between the steps results can result in broken hair.
Thus, there is a need for hair curling formulations and treatments that can provide improved conditioning benefit for hair when the hair is curled. Specifically, there is a need to provide long lasting moisturized feel, smooth feel, and manageability control to curled hair.
There is also a need for hair curling formulations and treatments that afford the ability to tune or select the level of curl imparted to hair.
There is also a need for hair curling formulations and treatments that can be applied to the hair as a single formulation.
Additionally, there is a need for hair curling formulations without a foul thiol or related odor.
Therefore, it is an object of this invention to provide improved curling formulations and curling methods for repairing and/or strengthening curled hair.
It is a further object of this invention to provide curling formulations and methods which can be used to tune or select the level of curl imparted to hair.
It is a further object of this invention to provide hair curling formulations and treatments that can be applied to the hair as a single formulation, as well as formulations without a foul thiol-based odor.